Copper-based alloys having high strength are of interest, e.g., in the manufacture of springs, relay elements, and wire connectors where, additionally, high electrical conductivity is desired. Considerable progress is represented in this respect by the development of Cu--Ni--Sn spinodal alloys by one of the present inventors; see, e.g., J. T. Plewes, "Spinodal Cu--Ni--Sn Alloys are Strong and Superductile", Metal Progress, July 1974, pp. 46-50 and J. T. Plewes, "High-Strength Cu--Ni--Sn Alloys by Thermomechanical Processing", Metallurgical Transactions A, Vol. 6A, March 1975, pp. 537-544. These alloys, in many instances, may advantageously replace customary Cu--Be or phosphor bronze alloys whose strength and formability are surpassed by the corresponding properties of suitably processed Cu--Ni--Sn alloys. (For example, a tensile strength exceeding 150,000 pounds per square inch in combination with area reduction to fracture exceeding 50 percent is obtainable in a Cu-9 weight percent Ni-6 weight percent Sn alloy.) However, while use of Cu--Ni--Sn alloys has led to significant savings, e.g., in the manufacture of wire connectors, recent increases in the price of tin have fostered interest in the development of further suitable alternatives.
Considered with respect to the invention were items concerning copper-antimony alloys, namely M. Hansen, Constitution of Binary Alloys, McGraw-Hill Book Company, 1958, pp,. 622-628; Precipitation from Solid Solution, American Society for Metals, 1959, page 367; and Mechanical Properties, Vol. 6, 1977, Trans-Tech Publications, page 62. Also considered were the papers by Nisaku Shibata, "The Equilibrium Diagram of the Complete Ternary System, Copper-Antimony-Nickel", Nippon Kinzoku Gakkai-Si, Vol. 4, 1940, pp. 269-289 and Vol. 5, 1941, pp. 12-25.